Subject: Re: [PATCH 4/6] net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction

From: kernel test robot <[email-masked]>
Date: Sun, 14 Aug 2022 23:49:24 +0800

Hi Dmitry,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on 058affafc65a74cf54499fb578b66ad0b18f939b]

url:    https://github.com/intel-lab-lkp/linux/commits/Dmitry-Safonov/net-crypto-Introduce-crypto_pool/20220727-041830
base:   058affafc65a74cf54499fb578b66ad0b18f939b
config: i386-randconfig-a005 (https://download.01.org/0day-ci/archive/20220814/[email-masked]/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/a4ee3ecdaada036ed6747ed86eaf7270d3f27bab
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Dmitry-Safonov/net-crypto-Introduce-crypto_pool/20220727-041830
        git checkout a4ee3ecdaada036ed6747ed86eaf7270d3f27bab
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash net/ipv4/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email-masked]>

All warnings (new ones prefixed by >>):

>> net/ipv4/tcp_ipv4.c:1174:5: warning: no previous prototype for '__tcp_md5_do_add' [-Wmissing-prototypes]
    1174 | int __tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
         |     ^~~~~~~~~~~~~~~~

vim +/__tcp_md5_do_add +1174 net/ipv4/tcp_ipv4.c

  1172	
  1173	/* This can be called on a newly created socket, from other files */
> 1174	int __tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
  1175			     int family, u8 prefixlen, int l3index, u8 flags,
  1176			     const u8 *newkey, u8 newkeylen, gfp_t gfp)
  1177	{
  1178		/* Add Key to the list */
  1179		struct tcp_md5sig_key *key;
  1180		struct tcp_sock *tp = tcp_sk(sk);
  1181		struct tcp_md5sig_info *md5sig;
  1182	
  1183		key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index, flags);
  1184		if (key) {
  1185			/* Pre-existing entry - just update that one.
  1186			 * Note that the key might be used concurrently.
  1187			 * data_race() is telling kcsan that we do not care of
  1188			 * key mismatches, since changing MD5 key on live flows
  1189			 * can lead to packet drops.
  1190			 */
  1191			data_race(memcpy(key->key, newkey, newkeylen));
  1192	
  1193			/* Pairs with READ_ONCE() in tcp_md5_hash_key().
  1194			 * Also note that a reader could catch new key->keylen value
  1195			 * but old key->key[], this is the reason we use __GFP_ZERO
  1196			 * at sock_kmalloc() time below these lines.
  1197			 */
  1198			WRITE_ONCE(key->keylen, newkeylen);
  1199	
  1200			return 0;
  1201		}
  1202	
  1203		md5sig = rcu_dereference_protected(tp->md5sig_info,
  1204						   lockdep_sock_is_held(sk));
  1205	
  1206		key = sock_kmalloc(sk, sizeof(*key), gfp | __GFP_ZERO);
  1207		if (!key)
  1208			return -ENOMEM;
  1209		if (!tcp_alloc_md5sig_pool()) {
  1210			sock_kfree_s(sk, key, sizeof(*key));
  1211			return -ENOMEM;
  1212		}
  1213	
  1214		memcpy(key->key, newkey, newkeylen);
  1215		key->keylen = newkeylen;
  1216		key->family = family;
  1217		key->prefixlen = prefixlen;
  1218		key->l3index = l3index;
  1219		key->flags = flags;
  1220		memcpy(&key->addr, addr,
  1221		       (IS_ENABLED(CONFIG_IPV6) && family == AF_INET6) ? sizeof(struct in6_addr) :
  1222									 sizeof(struct in_addr));
  1223		hlist_add_head_rcu(&key->node, &md5sig->head);
  1224		return 0;
  1225	}
  1226	

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